第一课、OpenGL绘制直线等等

//

//  main.c

//  opengl_ animationRect_0002

//

//  Created by  ch_soft on 12-1-16.

//  Copyright (c) 2012年 __MyCompanyName__. All rights reserved.

//

#include<stdio.h>

#include<GLUT/glut.h>

#include<OpenGL/gl.h> 

#include<OpenGL/glu.h>

//用于绘制窗口需要的图形

void RenderScene()

{

    //清除颜色缓冲区，即窗口的背景色

   glClear(GL_COLOR_BUFFER_BIT);

    

    //设置当前绘图使用的颜色

  glColor3f(0.0f,0.0f, 0.0f);

    

    //使用当前的颜色来绘制一个矩形

//    glRectf(100.0f, 150.0f, 150.0f, 100.0f);

    

//   1.画点

    GLfloat sizesPoint[2];//保存线宽的尺寸范围

    GLfloat stepPoint;//保存线宽度尺寸的最小间隔

    GLfloat curSizePoint;

    

   glGetFloatv(GL_POINT_SIZE_RANGE,sizesPoint);

   glGetFloatv(GL_POINT_SIZE_GRANULARITY,&stepPoint); 

    curSizePoint=sizesPoint[0];

    for (int i=0;i<25;i++) {

        glPointSize(curSizePoint); 

        glBegin(GL_POINTS);

        glVertex3f(25.0+i*8,200.0f,0.0f); 

        glEnd();

        curSizePoint +=stepPoint*2;

    }

    

    

//  2. 画直线

    

//    GLfloat sizesLine[2];//保存线宽的尺寸范围

//    GLfloat stepLine;//保存线宽度尺寸的最小间隔

    GLfloat curSizeLine=5;

//    glGetFloatv(GL_LINE_WIDTH_RANGE,sizesLine);

//    glGetFloatv(GL_LINE_WIDTH_GRANULARITY,&stepLine);

    glLineWidth(curSizeLine); 

   glBegin(GL_LINES);

   glVertex3f(25.0f,160.0f,0.0f);

   glVertex3f(225.0f,160.0f,0.0f); 

    

    glEnd();

    

//   3.画连续的直线

   glBegin(GL_LINE_STRIP);

   glVertex3f(25.0f,150.0f,0.0f);

   glVertex3f(100.0f,150.0f,0.0f); 

   glVertex3f(100.0f,130.0f,0.0f);

    glEnd();

    

   glBegin(GL_LINE_STRIP);

   glVertex3f(0.0f,0.0f,0.0f);

   glVertex3f(10.0f,10.0f,0.0f);

   glVertex3f(20.0f,5.0f,0.0f);

    glEnd();

    

//   4.画封闭式直线

   glBegin(GL_LINE_LOOP);

   glVertex3f(125.0f,150.0f,0.0f);

   glVertex3f(200.0f,150.0f,0.0f); 

   glVertex3f(200.0f,130.0f,0.0f);

    glEnd();

    

//   画虚线

   glEnable(GL_LINE_STIPPLE); 

    glLineStipple(1,0x00FF);//第一个参数是倍数，第二个参数是一个十六进制数，用来表示如何显示的

   glBegin(GL_LINES);

   glVertex3f(25.0f,120.0f,0.0f);

   glVertex3f(225.0f,120.0f,0.0f); 

    glEnd();

    

    

   glLineWidth(3);

   glLineStipple(1,0xFF0C); 

   glBegin(GL_LINES);

   glVertex3f(25.0f,80.0f,0.0f);

   glVertex3f(225.0f,80.0f,0.0f);

    glEnd();

    

    

   glLineStipple(4,0xFF0C); 

   glBegin(GL_LINES);

   glVertex3f(25.0f,40.0f,0.0f);

   glVertex3f(225.0f,40.0f,0.0f); 

    glEnd();

   glDisable(GL_LINE_STIPPLE);

   //刷新opengl命令队列

    glFlush();

}

//改变大小时调用的函数

void ChangeSize(GLsizei w,GLsizei h)

{

    if (h==0) {

        h=1;

    }

   //设置视区尺寸

    glViewport(0, 0, w, h);

    //重置坐标系统，使用投影变换复位

   glMatrixMode(GL_PROJECTION);

   glLoadIdentity();

    

    if (w<=h) {

       glOrtho (0.0f,250.0f, 0.0f,250.0f*h/w, 1.0f, -1.0f);

    }else

    {

       glOrtho (0.0f,250.0f*w/h, 0.0f,250.0f, 1.0f, -1.0f);

    }

   glMatrixMode(GL_MODELVIEW);

   glLoadIdentity();

}

//用于初始化，常用来设置场景的渲染状态

void SetupRC(void)

{

   glClearColor(1.0f,1.0f, 1.0f,1.0f);

}

int main(int argc,char** argv)

{

   //    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);

   //    glutCreateWindow("GLRect");

    

    glutInit(&argc, argv);

   //初始化GLUT库OpenGL窗口的显示模式

   glutInitDisplayMode (GLUT_SINGLE |GLUT_RGB |GLUT_DEPTH);

   glutInitWindowSize (500,500); 

   glutInitWindowPosition (100,100);

   glutCreateWindow (argv[0]);

    

    

   glutDisplayFunc(RenderScene);

   glutReshapeFunc(ChangeSize);

    

    SetupRC();

   glutMainLoop();

    

    return 0;

}